1,720,963 research outputs found
Ambiente e sistema endocrino: i distruttori endocrini
No full textMany chemical substances, both natural and synthetic, can have effects on the functioning of the endocrine system and, consequently, on the development of apparatus and systems. These molecules act by miming the hormone action with synergistic or antagonistic effects and they are named as endocrine disruptors (ED).
The ED use in the medical, agricultural and industrial field constantly puts the scientific community in front of a great challenge to assess the cost-benefit balance that comes from their use in many areas of modern human activities. At the same time, national and international institutions are called upon to draw up legislative protocols governing their use
Ambiente e sistema endocrino: il controllo dei fenomeni migratori
No full textEnvironment and endocrine system: the control on migrations. During migrations, entire populations of animal species move from one place to another searching more favourable conditions for reproduction and/or growth. Traditionally, the complex migratory behaviour has been the field of ethology studies; however, the endocrine system plays a crucial role in the coordination between environmental changes and the animals’ physiological changes necessary to migration. Some among the most investigated examples of this control are taken into consideration, which regard teleosts, reptiles and birds
NO in teh supramedullary neurons cluster of Tetraodon fluviatilis: a molecule for paracrine communication ?
No full textsono descritti i risulati di indagini istochimiche e immunoistochimiche che dimostrano la presenza di ossido nitrico nel cluster di neuroni sopramidollari di Tetraodon e viene proposto per tale molecola un ruolo paracrin
Histochemical and immunocytochemical localization of nitric oxide synthase in the supramedullary neurons of the pufferfish Tetraodon fluviatilis
No full textThe presence of the nitric oxide (NO) converting enzyme, constitutive neuronal NO synthase (nNOS), was investigated in the supramedullary neurons (SN) cluster of the pufferfish Tetraodon fluviatilis. The identification of NADPH diaphorase- (NADPHd-) positivity and the demonstration of nNOS with the BAS technique and with immunofluorescence together, strongly indicate the presence of a constitutive NO converting enzyme in SN cellular bodies and axons, and provides evidence that the SN cluster represents a distinct nitrergic neuronal system in the vertebrate CNS. The possible roles of NO in the cluster are discussed, including an involvement in communication among neurons and between neurons and the glial cells in the cluster
ACTH occurrence in teleosts supramedullary neuron clusters: a neuron-glial common language?
No full textThe cross-talk between neurons and glia is receiving increased attention because of its potential role in information processing in the nervous system. We choose the cluster of supramedullary neurons (SN) and glial cells of pufferfish as a suitable model for studying neuron-glial interactions, identifying the implicated cell types and the signalling involved. In particular, among pro-opiomelanocortin (POMC)-derived peptides, adrenocorticotrope hormone (ACTH)-immunopositivity was found both in SN and in microglial cells. The present results for the first time show the presence of ACTH in microglia of a vertebrate. The role of ACTH is discussed, including its possible neuroprotective function. Moreover, SN immunoreactivity supports the idea that ACTH participates in neurotransmission and/or neuromodulation. In addition to these possible functions, the hypothesis is put forward that ACTH represents a common language by which neurons and glial cells communicate with each other. (C) 2003 Elsevier Science (USA). All rights reserved
The supramedullary cells of the teleost Coris julis (L.): A noradrenergic neuronal system
Get PDFThis study, carried out on Coris julis (Labridae), is a contribution to the immunocytochemical characterization of fish supramedullary neurons. The significance of these giant cells has been debated since the beginning of the twentieth century. Our research provides the first evidence for a noradrenergic feature of this neuronal system. The possible role of supramedullary neurons as components of the autonomic nervous system is discussed. Moreover, the present results, taken together with our previous studies, surmise that this the first known case of co-localization of a neuropeptide (gastrin/CCK-like) and noradrenaline in the nervous system of teleosts
I neuroni del cluster di Diodon holacanthus (Osteichthyes): studio ultrastrutturale
No full textVengono descritti gli apsetti ultrastrutturali dei neuroni sopramidollari riuniti in cluster in Diodon, in confronto con quello dei n. sopramidollari allineati lungo il midollo presenti in altre specie di teleostei
DNA endoreplication in the clustered supramedullary neurons of the pufferfish Diodon holacanthus L. (Osteichthyes)
No full textDNA contents, ranging from 4C to more than 500C, were determined by a quantitative microfluorimetric assay in supramedullary neuron nuclei of the pufferfish Diodon holacanthus. The distribution of C values after ethidium bromide staining indicates an inter- and intra-individual variation in DNA contents which do not correspond to duplications of the total genome, suggesting that DNA replication is specific for particular genes (endoreplication). Moreover, the DNA content appears to be correlated with nuclear size. A relationship between the DNA amounts and the presence of AT- and GC-rich sequences has been shown. This work demonstrates, for the first time, DNA endoreplication in a specific neuronal type in vertebrates
Localization of the (TTAGGG)(n) telomeric repeat in the chromosomes of the pufferfish Tetraodon fluviatilis (Hamilton Buchanan) (Osteichthyes)
No full textIn order to characterise the telomeric repeats of the pufferfish Tetraodon fluviatilis, fluorescent in situ hybridization (FISH) was carried out on metaphase chromosomes using a PCR generated probe (TTAGGG)(n). Distinct signals have been observed on the telomeres of all the chromosomes and hybridization signals appears of uniform size and intensity. Moreover FISH experiment does not evidence any interstitial non-telomeric signal. As non-telomeric FISH signal has been used as a marker for karyotype evolution and for determining the evolutionary status of fish species, it could be supposed that the absence of non telomeric signals makes T. fluviatilis (Tetraodontiformes) an evolutionary ancient species in respect to Perciformes
Cytogenetic analysis of the pufferfish Tetraodon fluviatilis (Osteichthyes)
No full textBecause of their compact genome, pufferfish (Tetraodontiformes) have been proposed as a model for the study of the vertebrate genome. The genome of pufferfish is peculiar as it has the structural complexity of the genomes of higher vertebrates, but has small introns and lacks large clusters of highly repetitive sequences. Despite such interest, information about the genetics of pufferfish is still scanty. To fill this gap, we have performed a cytogenetic analysis of the pufferfish, Tetraodon fluviatilis, which can be maintained in an aquarium for a long time and, unlike the pufferfish, Fugu rubripes, it is not difficult to obtain. Karyotype analysis shows that T. fluviatilis has 2n = 42 with two metacentric chromosomes, four submetacentrics, two subtelocentrics and 34 acrocentrics. C-banding, followed by DAPI staining, showed that heterochromatin is essentially AT-rich and is located at centromeres. Staining of the same metaphase plates with CMA(3) showed the presence of four heterochromatic regions located on two pairs of submetacentric chromosomes. Silver staining and FISH with a 28S rDNA probe showed that these GC-rich regions are nucleolar organizing regions (NORs). Finally, regardless of the technique used, no difference in the chromosome complement was found between males and females
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